In a variety of circumstances, in particular in cases of emergency were it is wished to signal information to individuals located outside a building about potential dangers within the building, having a signalling device which can be shone through a window, such as a flashing light or the like, can prove very useful. This is particularly true in the case of terrorist attacks and the like where hostages and civilians are involved and the police or other paramilitary forces are hesitant to enter the premises for fear of escalating the situation, and where their knowledge of the position of assailants within the building is not known to those on the outside.
On the other hand, those persons confined to the inside of the building by the assailants may be the only source of knowledge of the location the assailants, for example that they are within their general vicinity, and provided those persons are appropriately equipped to signal information they can be a useful source of information to those located on the outside of the building who are hoping to diffuse the situation. This could be particularly useful in schools or the like where attacks are typically disorganised and assailants and potential victims located through out the school, also typically in rooms which have windows facing the outside. Additionally, such institutions have a staff, such as teachers, who can be trained and equipped appropriately.
On the other hand, recognition by an assailant that information is being transmitted to the outside might serve to escalate the situation with potentially lethal consequences and therefore an approach which hides this activity from the assailant would appear beneficial.
What is needed, therefore, and one aspect of the present invention, is an equipment which can be attached to a window or other transparent or translucent surface an used as a way to communicate information to others located on the other side of the surface using light in a manner which is not visible from the inside. An additional aspect of the present invention is that the equipment can be controlled when it is already installed on the transparent or translucent surface.